Likelihood of eruption remains at Ruapehu south of Rotorua
Thursday 29 November 2012
Results from the analysis of the Crater Lake samples taken recently suggest that the level of activity at Ruapehu, south of Rotorua, hasn't changed since last week. There are still indications of volcanic unrest, and despite Ruapehu being quiet at the moment, an eruption could occur with little or no warning.
The Aviation Colour Code remains at Yellow' and the Volcanic Alert Level remains at 1.'
The Volcanic Alert Level ranges from 0 to 5 and defines the current status at a volcano. Level 1 indicates a departure from typical background surface activity.
Aviation Colour Codes are based on four colours and are intended for quick reference only in the international civil aviation community. Code Yellow indicates that a volcano is experiencing signs of elevated unrest above known background levels.
Meanwhile GNS Science continues to closely monitor Ruapehu with scientists carrying out regular sampling of the mountain's Crater Lake. Analysis of the gas contained in the lake's water can provide information about the temperature beneath the lake. Repeating sampling and analysis through time allows scientists to assess how the temperature may be changing underground.
Lake temperatures remaining low (~ 20 degrees Celsius), indicates that gas may be trapped beneath the lake. This may increase the pressure underground, hence increasing the likelihood of an eruption.
Such a build-up of pressure beneath the Crater Lake is thought to have caused the 2007 eruption and a smaller eruption in 2006.